The present invention relates to a method and apparatus for generating isotherms in a temperature control system for a glass forehearth, and in particular to a technique for providing to the operator a visual representation of cross-sectional temperature profiles.
The control and display technique of the present invention is designed to be utilized in a forehearth for thermally conditioning molten glass received from a glass melting furnace, to be fed to a glassware forming machine. Such forehearths typically include an elongated refractory channel which is divided into a series of sections or zones, and are designed to bring the glass to a reduced temperature level and to achieve approximate thermal homogeneity. In the present state of the art, the operation of various heating and cooling methods is controlled by a human operator in response to a display of a plurality of temperature measurements taken at strategic locations within the forehearth channel. Inasmuch as thermocouples or other temperature sensor devices are very costly, it is accepted practice to use a limited number of temperature probes to measure temperatures at selected cross-sections along the forehearth channel.
A problem with this type of operator interface is that it is difficult for the operator to effectively visualize the temperature profile at these various cross-sections based upon the limited number of discrete readings taken by the thermocouples. In addition, where the temperature sensor readings may be included in a control loop to provide PID control or the like, the sophistication of the control technique may be limited by the use of only a discrete number of inputs to the control algorithm.
Accordingly, it is a principal object of the invention to provide an improved method and apparatus for generating temperature profiles of molten glass in cross-sections of forehearth channel. A particular object is to provide improved displays to the operator of such temperature profiles. A related object is to facilitate a forehearth operator's ability to visualize such temperature profiles.